Conventional electrophotographic or laser printers operate by using a roller or a series of rollers to pull a print media (typically a sheet of paper) from a paper tray, and to push the media to a registration roller assembly. The registration roller assembly aligns the media so that the edges of the media are parallel to the media path.
Once the media is properly aligned, the registration roller assembly passes the media to a photoconductor surface, such as a drum or belt. The photoconductor surface has a latent image on its surface formed by scanning a laser across the photoconductor surface. A difference in electrostatic charge density is created between the areas on the surface exposed and unexposed to the laser beam. A visible image is developed by toners that are selectively attracted to the photoconductor surface, either exposed or unexposed to light, depending on the relative electrostatic charges of the photoconductor surface, development electrode, and the toner. The photoconductor may be either positively or negatively charged, and the toner similarly may contain negatively or positively charged particles.
The media is given an electrostatic charge and passed close to the photoconductor surface. As the media passes close to the photoconductor surface, it pulls the toner from the photoconductor surface onto the media still in the pattern of the image developed from the photoconductor surface.
After receiving the image, the media is passed to a fuser. The fuser heats the toner image on the media, bonding the toner to the media.
The temperature of the fuser is critical. Rough media requires a higher fuser temperature than smooth media. If the temperature is too low, toner will not be adequately fused to the media. If the temperature is too high, the toner will be pulled from the media by the fuser. Either case results in an undesirable print defect. Additionally if the fuser temperature is too high, the media may curl or wrinkle.
Many laser printers have a fixed fuser temperature. The fixed fuser temperature is optimized for typical media types. Fixed fuser temperatures cannot accommodate media types that require more heat to properly fuse the toner to the media. Additionally, media types requiring lower fuser temperatures may be damaged by the heat of the fixed fuser temperatures.
In order to provide a laser printer that better accommodates a wide variety of print media, lasers printers have been developed that allow a user to control the fuser temperature by indicating to the printer which media type will be used. The fuser controller adjusts the fuser temperature according to the type of media. This type of fuser temperature control depends on the user to accurately indicate the media type. Additionally, when media type is changed, printing must be stopped to allow the user to indicate the new media type.